Integrated mechanical and circuit devices (i.e., integrated circuits and/or microelectromechanical (MEMS) devices) are formed on semiconductor substrates, or wafers. The wafers are then sawed into microelectronic dies (or “dice”), or semiconductor chips, with each die carrying a respective integrated circuit and/or MEMS component. Each semiconductor chip is mounted to a package or carrier substrate using either wirebonding or “flip-chip” connections. The packaged chip is then typically mounted to a circuit board, or motherboard, before being installed in a system, such as an electronic or a computing system.
Depending on the intended use of the semiconductor chip, one of the types of devices formed on the semiconductor substrate may be a capacitor. “On-chip” capacitors are often used on integrated circuit devices such as converters, radio frequency (RF) circuits, filters, and MEMS devices, such as pressure sensors and accelerometers. Such capacitors typically include two conductive plates separated by a gap (or a cavity) or an insulating material. Conductive traces, or runners, are also formed on the substrate to electrically connect each of the plates to an integrated circuit that may be located on the same die and is used to detect or calculate the capacitance between the two plates (Csense).
However, often a fringe capacitance (Cfringe) between one of the conductive plates and the conductive traces is also detected by the integrated circuit. The detection of this fringe capacitance is particularly problematic when the capacitor is used as a pressure sensor and one of the conductive plates is exposed to a fluid, such as in a tire. The fluid in a tire is typically air but may also include, for example, water and oil. These different fluids have different dielectric constants, and when contact is made with a portion of the capacitor, the fringe capacitance between the conductive plate and the conductive trace may be changed dramatically because of the change in dielectric constant. This change in fringe capacitance can adversely affect the accuracy of the capacitive sensing capabilities of the assembly.
Accordingly, it is desirable to provide a capacitor assembly with a reduced and controlled fringe capacitance between the conductive plates and the conductive traces. In addition, it is desirable to minimize the cost of manufacturing a capacitor assembly with a reduced and controlled fringe capacitance. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.